Is Determining the Number of distinct Prime Factors Polynomial?

Our current understanding of prime factorization states that it is hard to solve. The problem asks us to find the list of prime factors for an integer. For example, 18's prime factors are 3, 3, and 2. But since 3 is repeated, we only count it once.

But what about a slightly easier problem---finding how many prime factors a number has. Is there an efficient algorithm to do such a task?

In the 18 case, we still don't double count 3. So our algorithm should output 2 (the two prime factors are 3 and 2).

No problem involving factorization is known to be polynomial time, and these problems (formulated as decision problems in any reasonable way) are suspected to be NP-intermediate. The only problem which is known to be polynomial time is primality testing.

StackExchange Computer Science Q#162770, answer score: 6